In general, SCons tries to keep its error
messages short and informative.
That means we usually try to avoid showing
the stack traces that are familiar
to experienced Python programmers,
since they usually contain much more
information than is useful to most people.

In this case,
the error is pretty obvious.
But if it weren't,
and you wanted to try to get more information
about the error,
the --debug=stacktrace option
would show you exactly where in the SCons source code
the problem occurs:

Of course, if you do need to dive into the SCons source code,
we'd like to know if, or how,
the error messages or troubleshooting options
could have been improved to avoid that.
Not everyone has the necessary time or
Python skill to dive into the source code,
and we'd like to improve SCons
for those people as well...